Optical communication module and optical communication device

Abstract

An optical communication module and an optical communication device including the same are provided. For example, a first semiconductor chip on which a laser diode is formed and a second semiconductor chip on which a laser diode driver circuit, etc. for subjecting the laser diode to drive by current are formed are mounted on a package printed circuit board to be close to each other. Temperature detecting means is further formed on the second semiconductor chip (laser diode driver circuit, etc.). The temperature detecting means detects a temperature variation ΔT of the first semiconductor chip (laser diode) transmitted via a wiring in the package printed circuit board and controls the magnitude of the driving current of the laser diode driver circuit based on a detection result.

What is claimed is: 
     
       1. An optical communication module comprising:
 a first semiconductor chip having a laser diode outputting an optical signal being formed on the first semiconductor chip; 
 a first wiring; and 
 a second semiconductor chip connected to the first semiconductor chip via the first wiring, and having a driver circuit driving the laser diode by a first current being formed on second semiconductor chip, wherein 
 a driver control circuit, detecting a temperature variation of the first semiconductor chip transferred in heat via the first wiring and correcting the magnitude of the first current based on a detection result, is further formed on the second semiconductor chip; 
 the driver control circuit includes a temperature detecting circuit generating a first voltage increased in proportion to temperature and generates a driver control voltage obtained by adding a predetermined offset voltage to the first voltage; 
 the driver circuit includes a variable current source generating a current having a magnitude corresponding to the driver control voltage and determining a reference value of the first current; and 
 the temperature detecting circuit includes:
 first and second diodes having mutually different areas, 
 a constant current circuit causing an equal current to flow in the first diode and the second diode, and 
 
 a first amplifier circuit amplifying a voltage difference between a voltage generated at the first diode and a voltage generated at the second diode so as to output the first voltage. 
 
     
     
       2. The optical communication module according to  claim 1 , wherein
 the driver control circuit further includes:
 a variable amplifier circuit amplifying the driver control voltage by a first gain and supplying the amplified driver control voltage to the variable current source of the driver circuit, and 
 a setting circuit setting the first gain by a first set value. 
 
 
     
     
       3. The optical communication module according to  claim 1 , wherein
 the first wiring is a signal wiring for supplying the first current; and 
 the driver circuit further includes a waveform equalizer circuit compensating for waveform distortion of the first current generated in the first wiring. 
 
     
     
       4. The optical communication module according to  claim 1 , further comprising a first printed circuit board to which the first semiconductor chip and the second semiconductor chip are mounted, wherein
 the first wiring is a wiring formed in the first printed circuit board. 
 
     
     
       5. The optical communication module according to  claim 4 , wherein
 cooling means is provided to the second semiconductor chip. 
 
     
     
       6. The optical communication module according to  claim 1 , wherein
 the first semiconductor chip is mounted on a first surface of the second semiconductor chip; and 
 the first wiring is a metal wiring formed in a wiring layer in the second semiconductor chip. 
 
     
     
       7. An optical communication device comprising:
 a first wiring card mounting a first A optical communication connector and a first optical communication module; 
 a second wiring card mounting a second A optical communication connector and a second optical communication module; and 
 a first optical fiber cable connected between the first A optical communication connector and the second A optical communication connector and having a wiring length of several meters or less, wherein 
 the first optical communication module includes a first A semiconductor chip, a first laser diode transmitting a first optical signal to the first A optical communication connector formed on the first A semiconductor chip, a first wiring, and a first B semiconductor chip connected to the first A semiconductor chip via the first wiring; 
 the second optical communication module includes a second A semiconductor chip, first photodiode formed on the second A semiconductor chip, a second B semiconductor chip, and a first transimpedance amplifier circuit, the first photodiode converting the first optical signal received from the second A optical communication connector to an electric signal, and the first transimpedance amplifier circuit amplifying the current signal and converting the signal to a voltage signal; and 
 a first driver circuit driving the first laser diode by a first current, and a first driver control circuit detecting a temperature variation of the first A semiconductor chip transferred in heat via the first wiring and correcting magnitude of the first current based on a detection result are formed on the first B semiconductor chip. 
 
     
     
       8. The optical communication device according to  claim 7 , wherein
 the optical communication device further includes a second optical fiber cable, wherein 
 the first wiring card further includes a first B optical communication connector connected to a first end of the second optical fiber cable; 
 the second wiring card further includes a second B optical communication connector connected to a second end of the second optical fiber cable; 
 the second optical communication module further includes a second laser diode formed to transmit a second optical signal to the second B optical communication connector and a second C semiconductor chip connected to the second B semiconductor chip via a second wiring; 
 the first optical communication module further includes a first C semiconductor chip, a second photodiode formed on the first C semiconductor chip and converting the second optical signal received from the first B optical communication connector to an electric signal; 
 the first B semiconductor chip further has a second transimpedance amplifier circuit formed to amplify the current signal from the second photodiode and convert the signal to a voltage signal; and 
 a second driver circuit driving the second laser diode by a second current, and a second driver control circuit detecting a temperature variation of the second C semiconductor chip transferred in heat via the second wiring and correcting magnitude of the second current based on a detection result are further formed on the second B semiconductor chip. 
 
     
     
       9. The optical communication device according to  claim 7 , wherein
 the first driver control circuit includes a temperature detecting circuit generating a first voltage increased in proportion to temperature and generates a driver control voltage obtained by adding a predetermined offset voltage to the first voltage; and 
 the first driver control circuit includes a variable current source generating a current having magnitude corresponding to the driver control voltage and determining a reference value of the first current. 
 
     
     
       10. The optical communication device according to  claim 9 , wherein
 the temperature detecting circuit includes:
 first and second diodes having mutually different areas, 
 a constant current circuit causing an equal current to flow in the first diode and the second diode, and 
 a first amplifier circuit amplifying a voltage difference between a voltage generated at the first diode and a voltage generated at the second diode so as to output the first voltage. 
 
 
     
     
       11. The optical communication device according to  claim 9 , wherein
 the first optical communication module further includes a first printed circuit board mounting the first A semiconductor chip and the first B semiconductor chip; and 
 the first wiring is a wiring formed in the first printed circuit board. 
 
     
     
       12. The optical communication device according to  claim 11 , wherein
 cooling means is provided to the first B semiconductor chip. 
 
     
     
       13. The optical communication device according to  claim 9 , wherein
 the first A semiconductor chip is mounted on a first surface of the first B semiconductor chip; and 
 the first wiring is a metal wiring formed in a wiring layer in the first B semiconductor chip.